Section: Software

APF: state-of-the-art 3D audio library

Participants : Adrien David, George Drettakis.

This work was performed in collaboration with Jean-Christophe Lombardo of the DREAM research engineer service at INRIA Sophia-Antipolis Méditerranée. REVES has several audio research publications over the last 10 years, which correspond to a class of functionalities. The first component is the masking or culling algorithm, which aims at removing all the inaudible audio sources from a virtual scene based on perceptual metrics. The second component, called clustering, aims at grouping audio sources that are spatially close to each other and premix them to a representative cluster source, so that all spatialization related processing can be applied only on the representative premixed source [9] . Other audio topics were also considered and developed, like progressive and scalable frequency domain mixing, sound propagation, scalable reverberation, modal sound synthesis and contact sounds generation [1] .

In order to maintain all the knowledge in the group and re-use these technologies in the Immersive Space, a previous young engineer, a previous engineer (David Grelaud) wrote a fully documented audio library (APF) which gathers about 10 audio publications and 1 US patent. APF is a cross-platform, object oriented C++ API available on GForge. All the code has been re-implemented and a completely new software architecture resulted in a twofold increase in the speed of our algorithms. APF runs in the Immersive Space and uses the tracking system to spatialize virtual audio sources around the listener. It can also exploit personal Head Related Transfer Functions (HRTF).

We have implemented a network communications layer to create an audio rendering server on a separate machine, and the library is fully integrated into the osgVR platform.

APF has also been critical in establishing collaborations in the context of various grant proposals (EU and national).